Nanoparticles containing gold are nanometer-scale structures that exhibit a phenomenon known as surface plasmon resonance (SPR), which makes nanoparticles containing gold particularly useful in a broad array of applications. The broad array of applications, include but is not limited to optical sensing, photothermal destruction of tumor cells, targeted drug delivery, imaging, photonics, and electronics. In some instances, nanoparticles containing gold are gold alloys that include other metals such as copper, silver, palladium, and platinum.
Bare nanoparticles containing gold have a tendency to agglomerate in solution. Uncontrollable agglomeration of gold nanoparticles is undesirable because interaction between closely grouped gold nanoparticles substantially alters the optical properties of the gold nanoparticles, making them unreliable for optical sensing applications. It is known that providing an overcoating of a passivation material such as silica inhibits coalescence of gold nanoparticle cores. For biomedical applications, it is desirable for gold nanoparticles to have an overcoating of a passivation material that is nontoxic and that provides functionalized areas to which molecules of interest can adhere.
The overcoating of a non-spherical nanoparticle containing gold with silica yields a non-spherical nanostructure. At present, the production of non-spherical nanostructures containing gold results in inefficient yields due to a relatively high amount of byproduct material that must be removed before the non-spherical nanostructures are usable for applications. What is needed is a method for synthesizing non-spherical nanostructures that have coatings suitable for applications such as optical sensing.